Modular Wireless Real-Time Sensor/Actuator Network for Factory Automation Applications

Abstract

Modern factory facilities are characterized by highly flexible manufacturing cells and highly dynamic processes, where clusters of fixed or moving sensors and actuators have to be controlled in a limited space under stringent real-time and reliability constraints. In such demanding industrial environments, wireless systems can also be beneficial by improving flexibility, cutting cables, and enabling solutions, which are cumbersome or even not possible to realize with wireline systems, especially in controlling moving or rotating parts. In this paper, we present a conceptual study of a wireless real-time system dedicated for remote sensor/actuator control in production automation. System development is based on user requirements, which were extracted from customer interviews and a market research. Low level measurements of frequency-and space-selective wireless channels in a factory-like environment were carried out. System design aspects, i.e., network topology, multiple access schemes, and radio technologies, will be thoroughly reviewed. The performance of a first prototype implementation will be discussed with emphasis on timing behavior and power consumption, as sensors and actuators of the wireless system are intended to operate without power lines or batteries.Index Terms-Factory automation systems, multipath radio propagation, real-time communications, wireless sensor/actuator network.

Wireless Sensor Networks in Industrial Automation

“…Based on the analysis, the authors conclude, that the technology is suitable for applications in ISA usage classes 3 to 5 (see Section 2), but it is not adequate for applications in classes 0 to 2 (emergency actions to closed loop control). Two recent studies, (Körber & al., 2007); (Lill & Sikora, 2008) lend support to (PinedoFrausto & Garcia-Macias, 2008). Namely, they report the inapplicability of the current standard wireless solutions, such as IEEE 802.11, IEEE 802.15.1, IEEE 802.15.4 and ZigBee for hard real-time (5 ms trigger limit) applications.…”

“…Based on the initial results presented, the proposed approach could meet the 5 ms limit. In (Körber et al, 2007), development of a hard real-time sensor actuator is presented extensively, starting from user requirements and ending to a prototype implementation. The proposed approach applies the star network topology, combines frequency division multiple access with TDMA (F/TDMA), and a low-power commercial radio transceiver.…”

A Real-Time Wireless Communication System Based on 802.11 MAC

“…It has been successfully tested in a prototype network that adopts star topology and can manage up to 16 nodes with a refresh time of 128 ms. In (Heynicke et al, 2008;Krber et al, 2007), a gateway to interconnect hybrid wireless/wired control networks is proposed. The gateway is based on standard equipments such as the Chipcom CC2400 device by Texas Instruments.…”

Towards Reliable Wireless Industrial Communication With Real-Time Guarantees

“…Otherwise, will be zero. is calculated as (6) For calculations on the timing of message transmissions (for a graphical illustration of this see Fig. 3), a parameter for the bit rate of the physical link has to be introduced.…”

“…However, the advantages of wireless communication solutions have lately become interesting also for industrial networks. The need for reduced cabling, which leads to both the possibility of faster setup times for equipment and the possibility of communication in areas too harsh for using cables, and the added mobility have triggered research on the use of wireless communication in industrial systems like production systems including robots [2], control loops [3]- [5], and other automation applications [6]. Even while still using existing fieldbus standards, wireless alternatives have been studied as a substitute for cables [7]- [9].…”